Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$112.54	9.349%	$123.0614	$123.06	$123.05	$123.10
Purchase #2	$72.45	5.571%	$76.4862	$76.49	$76.50	$76.50
Purchase #3	$62.66	4.208%	$65.2967	$65.30	$65.30	$65.30
Purchase #4	$202.76	12.731%	$228.5734	$228.57	$228.55	$228.60
Purchase #5	$184.48	11.800%	$206.2486	$206.25	$206.25	$206.20
Purchase #6	$222.50	5.122%	$233.8965	$233.90	$233.90	$233.90
Purchase #7	$134.97	11.412%	$150.3728	$150.37	$150.35	$150.40
7 purchase totals =	$992.36		$1,083.9356	$1,083.94	$1,083.90	$1,084.00